fix(build_package.sh): set CROSS_COMPILE directly to aarch64-none-elf-

The variable `aarch64_none_elf_prefix` was removed in recent changes,
causing CROSS_COMPILE to be unset during RMM builds. Update the script
to assign CROSS_COMPILE explicitly to "aarch64-none-elf-" to fix the
toolchain path and ensure build consistency.

Change-Id: I666395ccad09a3a860372cf5e0447d9cbf4a48fe
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
1 file changed